diff -r abf45e1abfe3 src/video/SDL_video.c
--- a/src/video/SDL_video.c	Sat Apr 05 16:25:30 2014 -0700
+++ b/src/video/SDL_video.c	Sun Apr 06 16:25:31 2014 +0100
@@ -942,6 +942,8 @@
 int
 SDL_GetWindowDisplayIndex(SDL_Window * window)
 {
+    char* displayEnv;
+    char* displayDot;
     int displayIndex;
     int i, dist;
     int closest = -1;
@@ -951,6 +953,19 @@
     SDL_Rect rect;
 
     CHECK_WINDOW_MAGIC(window, -1);
+    displayEnv = SDL_getenv("DISPLAY");
+
+    if (displayEnv) {
+        displayDot = SDL_strchr(displayEnv, '.');
+
+        if (displayDot) {
+            displayIndex = SDL_atoi(displayDot + 1);
+
+            if (displayIndex < _this->num_displays) {
+                return displayIndex;
+            }
+        }
+    }
 
     if (SDL_WINDOWPOS_ISUNDEFINED(window->x) ||
         SDL_WINDOWPOS_ISCENTERED(window->x)) {